About teaching "coloring in the lines", a fellow art educator friend of mine
who has done published research on early child development explained it like
this -- when a child actually makes the line herself, she will be much more
inclined to "stay within the lines" than if the lines belong to someone else.
Coloring book type projects only add to the child's belief that if it isn't
perfect, and if it isn't exact, it isn't important. So to me, it can be the
first step toward making the child artistically inhibited from being creative.
When coloring or painting their own drawings, students could be encouraged to
"don't lose your lines" which is the exact same thing, but honors the
student's abilities rather than trivializing them.